Disterigma leucanthum A. C. Smith, Mem. New York Bot. Gard. 8(1): 50.  1952.  Type.  Ecuador.  Morona-Santiago:  Cordillera de Cutucú, ridge just S and W of Río Itzintza, 1525-1800 m, 17 Nov 1944 (fl), Camp E-1344 (holotype, US;  isotypes, F, NY;  photo of NY type NY neg. 9891).

        Epiphytic or terrestrial shrub, sometimes growing in mounds of Sphagnum, rooting along branches;  stem terete, striate, nitid, glabrous;  twigs subterete, complanate, obtusely angled, striate, puberulent, glabrate.  Leaves coriaceous, wrinkled when dry, elliptic to slightly ovate-elliptic, (1.1-)1.5-2.2 x 0.8-1.5 cm, base rounded or broadly obtuse, apex broadly obtuse, margin entire, slightly recurved, lamina ciliate, glabrate, also sparsely, minutely and subpersistently reddish glandular-fimbriate;  5-plinerved from base, midrib and lateral nerves raised above and slightly raised but obscure beneath, reticulate veinlets often prominent and raised above but impressed beneath;  petiole subterete, flattened above, rugose, 1.5-2.5 mm long, puberulent, glabrate.  Inflorescence axillary, of solitary flowers, surrounded at the base by many, inconspicuous, papyraceous, imbricate, suborbicular-oblong, ciliolate bracts to 1.5 mm long, with all parts of inflorescence densely and short-pilose with pale hairs ca. 0.1 mm long;  floral bract oblong-ovate, obtuse, ca. 1.5 mm long;  pedicel 1-2 mm long;  bracteoles broadly ovate-reniform, rounded, margins broadly imbricate, ca. 1-2 x 3 mm, ciliolate, marginally minutely glandular-fimbriate, covering about half the calyx hypanthium.  Flowers 4-merous, with calyx ca. 5-6 mm long;  hypanthium cylindric-campanulate, obscurely angled, ca. 1.5-2 mm long;  limb erect-spreading, deeply lobed, ca. 4 mm long;  lobes ovate, bluntly acute, 2.5-3 mm long and broad, at anthesis narrowly imbricate at base, marginally minutely glandular-fimbriate;  sinuses acute;  corolla fleshy, coriaceous when dry, cylindric to cylindric-urceolate, terete, ca. 9-9.5 mm long and ca. 5 mm diam., short-pilose mainly in distal half, white, the lobes spreading, oblong, obtuse, ca. 2-3 mm long;  stamen 8, ca. 6.8 mm long;  filaments 2-2.6 mm long, sparsely villose within distally;  anthers 4.5-5 mm long;  thecae ca. 1.8 mm long, the base rounded and sparsely hispid;  tubules 2, distinct, about equal with thecae, ca. 3 mm long, dehiscing by oval clefts 0.5-1 mm long;  nectariferous disc annular-pulvinate, glabrous;  style thick, equal to corolla, glabrous.  Berry not seen.

        Distribution.  Endemic to Ecuador and known only from the type collection;  from cloud forest, at 1525-1800 m altitude.  Rare and endangered.